Northland's Ultrasound Professionals
Phone: 09 974 8844
56 Kamo Rd, Kensington
Whangarei, 0112

The four most common stages to have an ultrasound

Dating Scan

The first scan is usually when you’re around 7-11weeks and is sometimes called the dating scan, because it estimates when your baby is due (the estimated date of delivery, or EDD). This scan also enables us to check if it’s a single or a multiple pregnancy. Unless there are concerns about the pregnancy it is better to wait to have this scan after 7 weeks as the images are clearer for you to see and better for us to measure. If you come before 7 weeks the baby will be less than 1cm in size and so the scan sometimes has to be performed transvaginally (placing the probe inside the vagina) to enable us to see the baby well enough to measure and to see the heartbeat.

We ask that you come with a full bladder for this scan as it usually allows us to get the best possible picture of the baby

Nuchal Translucency Scan (First trimester combined screening)

Your midwife or Doctor will discuss maternal serum screening (screening for Down’s syndrome and other chromosomal abnormalities) with you. If you decide to go ahead with this optional screening test you will be offered a scan between 11 weeks 2 days and 13 weeks 6 days (ideally 12 weeks). This is the only time that this scan can be performed. During this scan we will take measurements of your baby, specifically a small fluid area behind the baby’s neck called the nuchal translucency. We send these measurements to LabPlus in Auckland where a blood sample from you is also sent. LabPlus then calculate the risk or chance that your pregnancy is affected with Down Syndrome. Because this calculation is not carried out on site we are not able to give you the results straight away (on the day). LabPlus will contact your midwife with the results and she will discuss the results with you.

For more information about first trimester screening click here https://www.nsu.govt.nz/pregnancy-newborn-screening/antenatal-screening-down-syndrome-and-other-conditions

Nuchal scans are offered to all women, but you don’t have to accept it. Your choice will be respected if you decide not to have the scan, and you’ll be given the chance to discuss it with your maternity team before making your decision.

The 20 week (Anatomy) Scan

This is a detailed ultrasound scan, usually carried out when you are between 19 and 20 weeks pregnant. This scan checks for major physical abnormalities in your baby, although it can’t pick up every problem. So whilst a normal 20 week scan is very reassuring it cannot guarantee a healthy baby.

This scan usually takes around 40 minutes although it can take longer if the baby is in a difficult position or if a problem is detected.

The quality of the pictures we get depend on a number of factors including the position of the baby, the position, shape and structure of your womb, maternal BMI and the gestation of the pregnancy.

  1. Position of the baby – sometimes babies just lie in awkward positions. It’s just one of those things and we will do our best to try and encourage it to move to enable us to do all our checks.
  2. Your womb – every one of us is different, some wombs tilt forwards and some tilt backwards, sometimes these variations can make scanning a little harder and the pictures a little less clear.
  3. Maternal BMI – ultrasound works by sending sound waves into the body and ‘listening’ to the echoes that come back. The more tissue the sound has to travel through to reach the baby, the less clear the image. We can usually get clear enough images to do the checks that we need to do but sometimes with larger ladies we have to ask you to come back when the baby is a little bigger to help us see more clearly.
  4. Gestation of the pregnancy – ideally we like to do the anatomy scan around 19-20 weeks as this is the best time to do our checks for most women. To do the scan early means that the baby is smaller and it is harder to see the detail that we need to check and scanning too late in the pregnancy means that the baby is often very curled up and less likely to turn and move to show us what we need.

If for any of the reasons listed above we are unable to complete our checks on your baby we will arrange a follow up scan for you.

Fortunately most scans are normal, however some scans will show problems with the baby. Some of the problems we detect may resolve spontaneously during pregnancy, some may require treatment after the baby is born, or rarely a major problem that may affect the baby’s survival will be detected. If a problem is found this will be discussed with you and your midwife will be informed. If necessary your midwife will arrange appointments for you to see a specialist to discuss the long term implications for the health of your baby.

If you want to find out the sex of your baby, you can usually do so during the 20 week scan.

Tell the sonographer that you’d like to know your baby’s sex at the start of the scan. Be aware, though, that it’s not always possible for the sonographer to be 100% certain about your baby’s sex. For example, if your baby is lying in an awkward position, or if the image is not clear enough as discussed above.

Please also remember that the health of your baby is our priority and whilst we are happy to tell you the gender if we can see it is not the reason for the scan.

Although in theory it is sometimes possible to tell the sex of the baby at 12 weeks it is not our policy to do so as it is often difficult, time consuming and not as accurate as we would like.

Growth Scans

Routinely in twin pregnancies or at your midwife’s request, you might be asked to come for a growth scan. We do these to check that the baby is growing normally, that there is a normal amount of fluid around the baby, to check on the baby’s position and to check the position of the placenta.

This scan usually takes about 20 minutes.